Clarify names and move get_safe_block_hash to safe-block.md

fork_choice/safe-block.md

@@ -6,7 +6,8 @@
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 
 - [Introduction](#introduction)
-- [`get_safe_beacon_block`](#get_safe_beacon_block)
+- [`get_safe_beacon_block_root`](#get_safe_beacon_block_root)
+- [`get_safe_execution_payload_hash`](#get_safe_execution_payload_hash)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->
@@ -20,12 +21,26 @@ to expose a safe block to users.
 
 This section describes an algorithm to find a safe block.
 
-## `get_safe_beacon_block`
+## `get_safe_beacon_block_root`
 
 ```python
-def get_safe_beacon_block(store: Store) -> Root:
+def get_safe_beacon_block_root(store: Store) -> Root:
     # Use most recent justified block as a stopgap
     return store.justified_checkpoint.root
 ```
 *Note*: Currently safe block algorithm simply returns `store.justified_checkpoint.root`
 and is meant to be improved in the future.
+
+## `get_safe_execution_payload_hash`
+
+```python
+def get_safe_execution_payload_hash(store: Store) -> Hash32:
+    safe_block_root = get_safe_beacon_block_root(store)
+    safe_block = store.blocks[safe_block_root]
+
+    # Return Hash32() if no payload is yet justified
+    if compute_epoch_at_slot(safe_block.slot) >= BELLATRIX_FORK_EPOCH:
+        return safe_block.body.execution_payload.block_hash
+    else:
+        return Hash32()
+```

specs/bellatrix/fork-choice.md

@@ -75,20 +75,7 @@ As per EIP-3675, before a post-transition block is finalized, `notify_forkchoice
 
 ##### `safe_block_hash`
 
-The `safe_block_hash` parameter in a call to `notify_forkchoice_updated` function
-MUST be set to the return value of the following function:
-
-```python
-def get_safe_block_hash(store: Store) -> Hash32:
-    safe_block_root = get_safe_beacon_block(store)
-    safe_block = store.blocks[safe_block_root]
-
-    # Return Hash32() if no payload is yet justified
-    if compute_epoch_at_slot(safe_block.slot) >= BELLATRIX_FORK_EPOCH:
-        return safe_block.body.execution_payload.block_hash
-    else:
-        return Hash32()
-```
+The `safe_block_hash` parameter MUST be set to return value of `get_safe_execution_payload_hash(store: Store)` function.
 
 ## Helpers